Illuminated sign structure



Dec. 4, 1956 H. A. MEYRICK ET AL ILLUMINATED SIGN STRUCTURE 2 Sheets-Sheet 1 Filed Sept' 15. 1952 M6 6 I alczz,

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Filed Sept. 15, 1952 Dec. 4, 1956 H. A. MEYRICK ET AL 2,772,496

ILLUMINATED SIGN STRUCTURE Mm m 23% g A H55 49 50 46 45 Jhrfl :2

fl/d/erf5% United States Patent ILLUMINATED SIGN STRUCTURE Harold A. Meyrick, Nashville, and Walter E. Ellsworth, Indianapolis, Ind.

Application September 13, 1952, Serial No. 309,462

16 Claims. (Cl. 40130) The present invention relates generally to illuminated display structures or the like, and more particularly to illuminated display structures of the luminous discharge type, utilizing an ionizable gas.

Luminous discharge illuminated display structures or signs, heretofore available in the art, have utilized a hollow shell or envelope of glass or other suitable transparent material, such shell normally being elongated and provided with an electrode at each end with the envelope containing a suitable ionizable gas such as argon, neon or the like, whereby upon the application of an electrical energy to the electrodes, the gas will be ionized and give off light. To produce a desired display element, such as a character, word or design, the glass envelope is formed to simulate the shape of the particular character or element, and normally the glass envelope is constructed from elongated tubing, suitably bent or otherwise shaped to produce the desired character. Due to inherent limitations of the bent tubing type of construction, the variety of characters or designs which can be displayed are necessarily restricted. In those cases where words are to be displayed, it will be apparent that the utilization of continuous tubing to form the letters limits the shape of letters and the word, to either continuous script such as that obtained from normal handwriting, as distinguished from broken script letters such as that obtained in printing, or to semi-block printing in which portions of the tubing are doubled back upon themselves and other portions suitably coated with an opaque material to conceal portions of the tubing connecting adjacent letters. Thus, unless relatively large and expensive display structures are involved, the presently used illuminated display structures of the bent tube type are not easily constructed to present certain designs or types of characters and consequently are not entirely satisfactory, this being particularly true where the characters or designs are small in size as the ability to bend and shape the tubing becomes increasingly difficult. Consequently in smaller signs of this type where a block type of lettering is desired, the letters or characters appear more like those resulting from the use of a stencil.

Likewise, as the bent tubing type of sign normally requires relatively long current travel through the tube, often-times extending a number of feet, a relatively high voltage is required to produce illumination, with operating voltages normally running between 15,000 and 30,000 volts. The use of such high voltage obviously creates problems of insulation and also necessitates the use of voltage increasing equipment such as high voltage transformers. Similarly, as the voltage requirements are dependent upon the operational characteristics of the elongated tube type of structure and will vary with tube length, in large displays or signs utilizing a series of individual tubes, it is necessary to balance the system so that the single operating voltage will be correct for all of the separate tubes employed.

' The present invention is directed to a display structure of the luminous discharge type in which the illumi- Patented Dec. 4, 1956 "ice nated display elements need not be defined by the shape of the gas containing envelope, thereby eliminating the inherent linr'lgp tions. and disadvantages of the bent tubing type of str Mi -g and has among its objects the production of an llummated display structure, such as a sign or the like, in which a single gas containing chamber may be utilized and only selected portions of the gas in the chamber ionized to give off light, whereby the configuration of each respective display or illuminated portion of the device is substantially independent of the configurations of the other illuminated portions, as well as independent of the size and shape of the gas chamber.

Another object of the invention is the production of an illuminated display structure of the luminous discharge type which may be so designed that the current flow through the illuminated display portions thereof may be transverse to the exterior display face of the structure instead of in a direction parallel thereto, and in which one or more of the electrodes associated with each illuminated display portion may extend in the same direction as the outer display face of the structure, with the electrode adjacent the display face being so constructed that light produced may be visible through such electrode and the display face of the structure.

A further object of the invention is the production of a display structure in which the current travel through the display or illuminated portions of the device is relatively very short, whereby normal voltages of to 230 volts may be employed, and in which the current travel is uniform for all portions of the system regardless of the number of display or iluminated portions employed.

A further object of the invention is to provide a novel illuminated display structure having the above advantages which is simple and compact in construction and easily and inexpensively manufactured.

Other objects, features and attendant advantages of the present invention will be apparent to those skilled in the art from the disclosure herein given.

To this end our invention consists in the novel construction, arrangement and combination of parts herein shown and described and more particularly pointed out in the appended claims.

In the drawings wherein like reference characters indicate like or corresponding parts:

Fig. 1 is a plan view of one embodiment of an illuminated display structure constructed in accordance with the present invention;

Fig. 2 is a sectional view of the structure illustrated in Fig. 1, taken approximately on the line 22 of Fig. 1;

Fig. 3 is a transverse sectional view taken approximately on the line 3-3 of Fig. 1',

Fig. 4 is a transverse view taken approximately on the line 44 of Fig. 1;

Fig. 5 is a plan view similar to Fig. 1 of a second form of the invention;

Fig. 6 is a sectional view of the structure illustrated in Fig. 5, taken approximately on the line 66 of Fig. 5;

Fig. 7 is a sectional view taken approximately on the line 7-7 of Fig. 5;

Fig. 8 is a sectional view taken approximately on the line 8-8 of Fig. 5

Fig. 9 is a plan view similar to Fig. 1 of still another embodiment of the invention;

Fig. 10 is a sectional view of the section illustrated in Fig. 9 taken approximately on line Ill-10 of Fig. 9, and V Fig. 11 is a transverse sectional view taken approximately on the line 11-11 of Fig. 9.

...The present invention is illustrated in connection with a sign structure or the like, and contemplates the utilization of a display member of suitable material which will transmit light therethrough, illustrated in the drawings as a flat sheet of glass or plastic, the exterior surface of which forms the display face of the device. Cooperable with the lighttransrnitting member is a second member which extends parallel to the display member with the periphery of the respective members being suitably connected to form a sealed space therebetween which may be filled with an ionizable gas. Positioned in the gas chamber thus formed are a plurality 'ol ie iiictrodes, two electrodes being provided for each c'hai gr or design desired, with each pair of electrodes b'e i'rig oppositely spaced from one another in parallel relation and extending parallel to the display member. As hereinafter described, the electrode adjacent the display member may be constructed of an electrically conductive material so formed that light may pass therethrough, whereby illumination resulting from the passage of electricity through the gas between the two electrodes will be visible through the display member and the adjacent electrode. Obviously, in such a construction the electrodes may be formed with any desired configuration to produce a desired illuminated design, letter or character.

Referring to the drawings and particularly to Figs. 1 through 3, the illuminated display or sign structure illustrated includes a hollow member 1, illustrated in the present instance as comprising a pair of spaced apart parallel plates 2 and 3, constructed of a light transmitting, electrically non-conductive material such as glass or plastic, substantially co-extensive in size with the peripheral edges of the plates being sealed by any suitable means, as for example, longitudinally extending strips or members 4 and 5 and end members 6 and 7, with the joint between the plates and members being sealed by bonding or suitable cement 8 to form a sealed enclosure between the plates 2 and 3.

The inner opposed faces of the plates 2 and 3 are provided with repsective coatings 9 and 11, or a suitable transparent electrically-conductive material, as for example, a minutely thin layer of aluminum or other suitable material vaporized or otherwise deposited on the respective surfaces. If desired, glass panes having transparent conductive coatings on the surface thereof may be obtained commercially through a variety of companies including amongst which are: The Corning Glass Works, Corning, New York; The Libby Owens Company, and the Pittsburgh Plate Glass Company. One such product manufactured and sold commercially by The Corning Glass Works is marketed under the trademark Pyrex Brand E-C Radiant Glass Panels" and a description of the characteristics of this glass may be obtained from a sales brochure of the Corning Glass Company, No. B-86.

The portions of the sign to be illuminated shown in Fig. 1; namely, the letters forming the word S I G N are defined in the present instance by a non-conductive or insulating layer or coating 13, 14, superimposed on the respective conductive coatings 9, 11, the letters being formed by openings in the layer l3-and the openings 16 in the layer 14, whereby the cxposedportions of the respective conductive coatings 9, 11 are formed in the shape of the letters S I G N. In the embodiment of the invention illustrated, the openings in the layer 14 are of the same size and shape as the corresponding openings 15 in the layer 13 adjacent the front faces of the structure. The respective conductive coatings 9, 11 are adapted to be coupled across a source of electric power by means of conducting strips 17, 18, which respectively contact the conductive coatings 9, 11, and each form terminal posts to which one side of the electric power source may be connected.

It will be apparent that each of the exposed portions of the respective conductive coatings form an electrode, with each pair of oppositely disposed electrodes cooperating with the ionizablegas contained within the structure to form an elemental arc discharge tube. Thus, upon the inclusion of the conductive coatings through terminal strips 17, 18 in aclosed electric circuit, ionization ofithe gas takes place between each pair of oppositely tit) disposed portions of the respective conductive coatings, thereby producing illumination which can be viewed through the conductive coating to produce an illuminated letter or design. As each cooperable pair of electrodes thus formed, in effect, comprises its own are discharge tube; the sign illustrated may be considered as a plurality of luminous discharge elements contained within a single gas chamber or envelope, with the configuration or shape of the letter or design to be illuminated being substantially independent of the shape of the gas chamber or envelope, as contrasted with pervious structures wherein the shape of the illuminated display element is derived from the shape of the gas-containing envelopes'as for example, bent tube type of structure.

It will be particularly noted that in the construction just described, the distance between each pair of cooperating electrodes is the same, so that the system remains balanced regardless of the number of pairs of electrodes employed. Likewise, as the distance between each pair of cooperating electrodes is relatively very short, low operating voltages may be empolyed, normal line voltages of to 230 volts, which are readily available, being satisfactory for operation of the device. Consequently, the use of high voltage transformers is eliminated.

It will be apparent in the sign illustrated, that as the display elements comprising the letters S I G N are defined by the open portions in the coatings or layers 13, 14 overlying the conductive coatings, the unexposed portions of the latter function merely as conductors operatively connecting the respective exposed portions with the terminal strips 17, 18. Consequently, the electrodes could be formed by depositing the conductive material on the surfaces of the plates 2, 3 only where illumination is to be produced, in which case each electrode would be formed by a conductive coating of the desired shape and size, the remaining portion of the inner surface of the plates 2, 3 remaining uncoated as hereinafter described. The present construction, however, offers advantages in simplicity of manufacture and, as coated plates are commercially procurable, enables the inexpensive production of such a display structure.

In certain cases, as for example, in relatively large structures, it may be desirable to incorporate one or more spacer blocks 19 between the plates 2 and 3 to provide a more rigid structure, the blocks being operatively secured to the plates 2, 3 by cement or other suitable means. Provision may also be made for evacuating the interior of the structure and filling it with the ionizable gas, and for this purpose the structure illustrated in Figs. 1 to 4 may be provided with a'small passageway 21 in one of the peripheral members, such as the longitudinal member 5, with such passageway ultimately being sealed by a suitable closure member or plug 22.

Obviously, in utilizing the structure above described, colored effects may be obtained by selecting a desired one of the ionizable gases-argon, neon, linde, etc., to produce an illumination of the desired color. Similarly, novel colored eitects may be obtained by incorporating a color medium in the conductive coatings, or one or more transparent colored coatings or laminations on all or parts of the exterior surfaces of the gas container or envelope.

The construction illustrated in Figs. 5 to 8 is similar to that just described, the main difference being in the manner in which the illuminable. portions are defined. Referring to Figs. 5 and 6, the display structure illustrated includes a member 30 comprising a pair of spaced apart parallel plates 31, 32 constructed of a light transmitting or electrically transparent non-conductive material, such as glass or plastic. Formed on the adjacent surfaces-of eachof the spaced apart plates 31, 32 is a light-transmitting or transparent, electrically conductive coating 33, 34, respectively,-similar to the coatings 9,-11 on theplates 2, 3.

Disposed between the conductively coated surface 33, 34 of plates 31, 32, respectively, is a spacer block 35 constructed of an electrical insulating material, and having a number of open spaces 36 therein forming the characters desired to be exhibited. The open spaces 36 extend through the entire thickness of the block 35 so that with the block being positioned between the conductive surfaces of plates 31, 32, the conductive coatings 33, 34 are exposed on opposite sides of the character forming spaces 36. The edges of plates 31, 32 and insulating blocks 35 are secured together by a glass weld 37, or some other means so as to sealably enclose the spaces 36 forming the characters to be exhibited. Each of the spaces or characters 36 is inter-connected with the adjacent character through a plurality of insulated passageways 38, the construction of which is best illustrated in Figs. 7 and 8 of the drawings, formed in the insulating block 35. Upon the plates 32 and spacer block 35 being entirely assembled, the spaces 36 may be evacuated by means of passageways 38 and filled with an ionizable gas. With the spaces 36 filled with an ionizable gas, each of the spaces comprises an elemental arc discharge tube in which the exposed conductive surfaces 33, 34, on opposite sides thereof, serve as electrodes. The electrically conductive surface 33 is adapted to be coupled across by means of a conductive strip 41 contacting the transparent conductive surface 33, and terminating in a terminal post 42 to which one side of the electric power source can be connected, and the remaining transparent conductive surface 34 is likewise connected through a conductive strip 43 terminating in a terminal post 44 to which the remaining side of the aforementioned source of electric power may be connected.

Upon the above-described display structure being included in a closed electrical circuit, those portions of the transparent conductive coating being exposed by the open spaces or characters 36 act in the well known manner of electrodes of luminous discharge tubes and bring about a breakdown or ionization of the gases enclosed by the spaces, causing the same to ignite and give off illumination. This illumination can then be viewed through the transparent conductive coating, which may be colored if desired, or color may be obtained by utilizing a suitable one of the ionizable gases, argon, neon, linde, etc.

Referring now to Figs. 9 and of the drawings, a sign structure similar in many respects to the display structure disclosed in Fig. 1, is illustrated. The novel illuminated sign structure shown in Figs. 9 and 10 includes a member 45, and a pair of spaced apart parallel plates 46 and 47 constructed of a light-transmitting or transparent, non-conductive material. The transparent plates 46, 47 are spaced apart by means including a plurality of spacing blocks 48 disposed between adjacent faces of the plates, and a plurality of edge blocks 49a, 49b, which serve to sealably close the space between the plates 46, 47. Disposed or otherwise formed on the adjacent faces of the spaced apart plates 46, 47 are a plurality of opposed areas 50 having transparent, electrically conductive coatings thereon which, as is best shown in Figs. 9 and 11 of the drawings, each pair of opposed areas form the characters desired to be exhibited. The characters or coatings 50 on upper plate 46 engage or contact a pair of terminal strips 51 adapted to be connected in parallel across one side of a source of electrical power, and the corresponding characters or coatings on lower plate 47 engage or contact a pair of terminal strips 52 adapted to be connected in parallel across the remaining side of the source of electrical energy, the strips 51, 52 being insulated from each other by the edge blocks 4% preventing discharge and illumination therebetween. Each of the terminal strips 51, 52 have terminal posts formed on one or more exposed ends thereof to which lead in wires from the source of electrical power may be connected. Thus, the transparent electrically conductive letters or coatings 50 serve as 6 electrodes, and by evacuating the enclosed space between plates 46 and 47 and filling the same with an ionizable gas, the areas immediately between the cooperable pairs of characters formed by conductive areas 50 will act as elemental arc discharge tubes.

Upon the display structure illustrated in Figs. 9 and 10 being in a closed electrical circuit, the opposed conductive areas 50 will act in the well known manner of electrodes in standard luminous discharge tubes and cause a break down or ionization of the ionizable gas disposed between the cooperablc letters formed by the opposed conductive areas, thereby causing the characters to become illuminated, this illumination being visible at the exterior of the structure because of the transparent or light-transmitting nature of the plates 46, 47 and that of the conductive coatings 50. While some slight fringe effects may occur because of conduction through gas which is not directly between the cooperable characters, such fringe effect will be barely perceptible, and will not impair satisfactory overall definition of the display structure.

It will be appreciated, in connection with all forms of the invention illustrated, that while we have disclosed a display structure utilizing a pair of transparent platelike members having a conductive coating thereon through which light is visible, in a large number of the applications of the present invention, it is not necessary or desirable to construct the rear face of the structure of a material through which light may be transmitted. For example, in some cases it may be desirable to construct the rear member, corresponding to the plates 3, 31 and 46 from metal or the like, in which case the electrodes associated therewith may be formed from the member itself. Likewise, while we have illustrated the electrode-carrying members as comprising fiat surfaces, if desired, these members could be correspondingly curved or otherwise shaped to achieve novel effects. It might also be mentioned that where more ornate structures are desired, the front member and, if desired, also the rear member may be provided with raised or embossed-like letters or characters or other novel effects may be produced by individually forming the letters or designs on the display portions of the structure. However, in such cases the viewing portions of the structure would have to be designed and manufactured for each particular application, thereby considerably increasing the cost of manufacture.

In particular applications of the present invention, it may be found desirable to vary the shape of each respective pair of cooperable electrodes, whereby each pair is not co-extensive in size and shape as illustrated in the drawings, or to construct desired portions of the conducting material adjacent the display face of the structure in such a manner that light will be visible therethrough, thus producing different novel visual effects when the device is in operation. Likewise, in many applications of the present invention, it may not be desirable to form the rear electrode in the same or similar configuration to that of the electrode adjacent the display face of the structure, in which case the entire surface of the rear electrode could be conductive, so that in effect one large electrode would be employed with a plurality of smaller electrodes of desired configurations. In such case the one large common electrode would still be insulated at any point or points where an undesired discharge might take place, as for example, between the common electrode and exposed portions of conducting material operatively connecting the respective individual electrodes adjacent the display face of the structure. Such insulation, however, would be comparable merely to the insulation of the terminal strips 51, 52 by the members 49 in the construction illustrated in Figs. 9 to 11.

It will be apparent from the above disclosure that we have provided a display structure, particularly adapted for use as a sign or the like, in which the configurations of the illuminated portions of the device are substantially independent of the shape of the gas-containing envelope, and in which a plurality of electrodes may be utilized in a single gas chamber. Consequently, the present invention readily adapts itself to production line techniques and enables the production of a basic display structure which may be easily and inexpensively adapted to present substantially any type of character or design, and where a number of characters or letters are utilized, each may be given a desired configuration independent of the shape of any other character to be utilized in the finished structure.

While we have illustrated the electrodes as being formed from a conductive, light-transmitting material deposited upon the surfaces of the particular members, the term light-transmitting conducting material" as used herein, is intended to cover an electrode of any suitable conductive material which may be so produced or fabricated that it will not prevent the illumination produced from being visible at its exterior surface. Other examples of such materials are finely woven metallic screens and finely perforated metal.

Having thus described our invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of our invention; hence, we do not wish to be understood as limiting ourselves to the exact form, construction, arrangement, and combination of parts herein shown and de scribed, or uses mentioned.

What we claim as new and desire to secure by Letters Patent is:

l. A display structure including a member of lighttransmitting material having closely spaced cooperable electrodes providing indicia means formed thereon by a transparent light-transmitting, electrically conductive coating material, said member defining an enclosed space between said cooperable electrodes operatively mounted on opposite closely spaced inner faces of the member forming the enclosed space, and an ionizable gas contained within said enclosed space and between said spaced cooperable electrodes.

2. A display structure including a member comprising a pair of closely spaced parallel plates of light-transmitting material having a cooperable character formed thereon by a transparent light-transmitting, electrically conductive coating material on opposite closely spaced inner faces of the plates, said plates defining an enclosed space, and an ionizable gas contained Within said enclosed space and between said electrically conductive light-transmitting characters.

3. A display structure including a member of lighttransmitting material having cooperable characters formed thereon by a transparent electrically conductive coating material, said member defining an enclosed space between said cooperable characters operatively mounted on opposite closely spaced inner faces of the member forming the enclosed spaces, and an ionizable gas contained within said enclosed space and between said cooperable characters.

4. A display structure including a member comprising a pair of substantially closely spaced parallel plates of transparent material, characters complementally formed on said spaced plates by transparent electrically conductive coating material, the space between said plates being sealably enclosed, the distance between the parallel plates such that voltages within the range of from substantially 115 to 230 volts may be discharged thereacross through an ionizable gas, and the ionizable gas contained within said sealably enclosed space between the cooperable characters formed on said plates.

5. A display structure including a member comprising a pair of closely spaced parallel plates of light-transmitting material, a transparent lighttransmitting conductive coating formed on opposite adjacent inner surfaces of said spaced plates, an insulaitng spacer block having open spaces forming characters positioned between the conductive surfaces of said closely spaced plates, said plates and said spacer block being sealably closed around the edges thereof, and an ionizable gas contained Within said character forming spaces.

6. A display structure including a member comprising a pair of closely spaced parallel transparent plates, a transparent conductive coating formed on opposite inner surfaces of said spaced plates, a spacer block constructed of an electrical insulating material and having open spaces forming characters, electrically insulated passageways operatively interconnecting said character forming spaces, said spacer block being positioned between the conductive surfaces of said plates, and said plates and said spacer block being secured together to sealably enclose said character forming spaces, an ionizable gas contained within said spaces and said electrically insulated passageways, and terminal means for coupling said transparent conductive coatings across a source of electrical power.

7. A display structure including a member comprising a pair of spaced parallel plates of light-transmitting material, a transparent electrically conductive coating superposed on opposite inner surfaces of said spaced plates and forming cooperable characters, the space between said spaced plates being sealably enclosed, the distance between said characters formed on said spaced plates such that voltages within the range of from substantially to 230 volts may be discharged thereacross through an ionizable gas, and the ionizable gas contained within said sealably enclosed space and between the cooperable characters formed on said plates.

8. A display structure including a member comprising a pair of spaced parallel plates of light-transmitting material, a plurality of transparent light-transmitting electrically conductive coatings forming cooperable characters on opposite contiguous inner surfaces of said spaced plates, the space between said spaced plates being sealably enclosed, and an ionizable gas contained within said sealably enclosed space and between the cooperable characters formed on said plates.

9. A display structure including a member comprising a pair of spaced parallel plates of transparent material, a plurality of transparent electrically conductive coatings forming cooperable characters on opposite inner surfaces of said spaced plates, means for maintaining said plates in spaced relation and securing the edges thereof together to sealably enclose the space therebetween, an ionizable gas contained within said sealably enclosed space and between the cooperable characters formed on said plates, and terminal means for coupling said plurality of electrically conductive coatings across a source of electric power.

10. A display structure including a member comprising a pair of spaced parallel plates of light-transmitting material, a transparent light-transmitting conductive coating formed on opposite inner surfaces of said spaced plates, a layer of electrical insulating material superposed on said conductive coatings to blank out those areas where it is desired that no illumination take place, the unblanked areas of said transparent light-transmitting conductive coatings forming cooperable electrodes, and the space between said spaced apart plates being sealably enclosed, and an ionizable gas contained within said sealably enclosed space and between said electrodes.

11. In an illuminating device providing an illuminated area forming a symbol, the combination of a hollow structure having a transparent display wall, a transparent coating providing electrical conducting element positioned within said hollow structure and extending generally in substantially the same direction as said display wall upon which the transparent coating is applied, a second electrical conducting element closely positioned within said structure oppositely adjacent to but spaced from and cooperable with said first element, said electrical conducting elements providing an illuminated area forming a symbol, and an ionizable gas contained within said structure and between said elements, said conducting ele ments being shaped to provide a predetermined illuminable area smaller in size than the area of said display wall.

12. In an illuminating device providing an illuminated area forming a symbol, the combination of a hollow envelope of relatively large dimensions in two directions, and of relatively small dimensions in the third direction, one of the walls of said envelope having the larger two of the three dimensions being constructed of a light-transmitting material providing a display wall, a transparent coating providing an electrical conducting element applied to and extending in substantially the same direction as the inner surface of said display wall, said element being so constructed that light may pass therethrough providing an illuminated area forming a symbol, the operative area of said element being less than the area of said display wall, a second electrical conducting element closely positioned within said hollow envelope, oppositely and uniformly spaced from the inner face of said first element, and an ionizable gas contained within said hollow envelope and between said closely spaced elements.

13. In a hollow display structure, the combination of a light-transmitting member providing a display wall, a transparent coating providing an electrical conducting element of predetermined configuration superimposed upon an inner face of said light-transmitting member, said element being so constructed that light may pass therethrough, a second electrical conducting element uniformly and closely spaced from and cooperably related to said first element, each of said elements operatively mounted within the hollow display structure, means cooperable with said light-transmitting member for operatively enclosing cooperable portions of said elements, and an ionizable gas contained within said enclosed space between said elements.

14. In a hollow display structure, the combination of a light-transmitting member providing a display wall, a plurality of electrical conducting elements of predetermined configuration associated With said member and operatively positioned within the hollow display structure, said elements being so constructed that light may pass therethrough, means forming a second electrical conducting element for each of said first elements, uniformly and closely spaced from and cooperably related to the respective first elements and oppositely positioned within said hollow display structure to said first elements, means associated with said light-transmitting member 10 for operatively enclosing cooperable portions of said elements, and an ionizable gas contained within said enclosed space between said elements.

15. In a hollow display structure, the combination of a light-transmitting member providing a display wall, a transparent coating providing an electrical conducting element of predetermined configuration associated with an inner face of said member, said element being so constructed that light may pass therethrough, a second electrical conducting element within said hollow display structure, oppositely and closely spaced a relatively short distance from and cooperably related to said first element, means associated with said light-transmitting member for operatively enclosing cooperable portions of said elements, and an ionizable gas contained within said enclosed space between said elements, the distance between said elements being sufficiently short to produce ionization of such gas and illumination upon the application of voltages within the range of from substantially to 230 volts to said conducting elements.

16. A hollow display structure including a member comprising a pair of spaced apart parallel plates of transparent material, a transparent conductive coating formed on opposite adjacent inner surfaces of said spaced apart plates, a layer of electrical insulating material superposed on said conductive coatings to blank out those areas where it is desired that no characters appear, correspondingly unblanked areas of said transparent conductive coatings forming cooperable electrodes, means for maintaining said plates in spaced apart relation and securing the edges thereof together to sealably enclose the space therebetween, an ionizable gas contained within said sealably enclosed space and between the cooperable electrodes formed on said plates, and terminal means for coupling said plurality of electrically conductive coatings across a source of electric power.

References Cited in the file of this patent UNITED STATES PATENTS 

